Measurements and analyses of the temperature distribution on the surface of 3-phase cable terminal in service

The power equipment in service will give out heat causing a rise in temperature of its insulation system. If the insulation system is degraded, or the operating condition is changed, then abnormal thermal distribution of the insulation system may appear. Sometimes, the condition of the insulation system may be monitored by measuring the surface temperature of insulation system, some hidden defects can be detected. We have investigated the surface thermal distribution of cable terminal in service, and found some typical distributions for the test samples with different defects, such as 3-phased current unbalance, overheat at three-forked position and overheat in a local area. Finally, the measuring results based on heat-transfer theory are discussed.